. Morphology of gymnosperms. Gymnosperms; Plant morphology. 34 MORPHOLOGY OF GYMNOSPERMS "nucellar beak," which is said to "arise from the floor of the pollen chamber," is in reality a core of tissue left intact in the formation of the pollen chamber. An important feature to note in the seeds of this group is that the open tube of the pollen chamber projects a little through the micropyle, so that the passage for the entrance of the pollen grains is not furnished by the micropyle, but by the pro- truding nucellar beak (86, 87).. Fig. 29. —Lagenosloma ovoidcs: longitudinal s
. Morphology of gymnosperms. Gymnosperms; Plant morphology. 34 MORPHOLOGY OF GYMNOSPERMS "nucellar beak," which is said to "arise from the floor of the pollen chamber," is in reality a core of tissue left intact in the formation of the pollen chamber. An important feature to note in the seeds of this group is that the open tube of the pollen chamber projects a little through the micropyle, so that the passage for the entrance of the pollen grains is not furnished by the micropyle, but by the pro- truding nucellar beak (86, 87).. Fig. 29. —Lagenosloma ovoidcs: longitudinal section through apex of seed- shown in fig. 28, illustrating an earl)' stage in the formation of the pollen chamber; n, central portion of nucellus which becomes the core shown in fig. 27; «', outer hard part of nucellus; p, beginning of pollen chamber; m, megaspore membrane; i, integument; X36. The impression described as Lagenostoma Sindairii (51) shows the same type of seed (fig. 26), so far as external characters are con- cerned, and furthermore it shows its connection with foliage of the Sphenopteris type. It is evident that in comparing these seeds with those of living gymnosperms they must be regarded as resembling those of cycads, with decided peculiarities of their own. It is still further evident that such seeds are very far from being primitive in structure, and are no more suggestive of the origin of seeds in general than are the seeds of existing seed plants. Physostoma.—Recently Oliver (85) has restored this genus, described first by Williamson (2), but later referred by him (3) to. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John Merle, 1851-1928; Chamberlain, Charles Joseph, b. 1863; Coulter, John Merle, 1851-1928. Morphology of spermatophytes. Part I. Gymnosperms. Chicago, U
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